---
title: Record Final Object after Streaming Object
description: Learn how to record the final object after streaming an object using the AI SDK and Node
tags: ['node', 'streaming', 'structured data']
---

# Record Final Object after Streaming Object

When you're streaming structured data, you may want to record the final object for logging or other purposes.

## `onFinish` Callback

You can use the `onFinish` callback to record the final object.
It is called when the stream is finished.

The `object` parameter contains the final object, or `undefined` if the type validation fails.
There is also an `error` parameter that contains error when e.g. the object does not match the schema.

```ts file='index.ts' highlight={"15-23"}
import { streamObject } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
  onFinish({ object, error }) {
    // handle type validation failure (when the object does not match the schema):
    if (object === undefined) {
      console.error('Error:', error);
      return;
    }

    console.log('Final object:', JSON.stringify(object, null, 2));
  },
});
```

## `object` Promise

The [`streamObject`](/docs/reference/ai-sdk-core/stream-object) result contains an `object` promise that resolves to the final object.
The object is fully typed. When the type validation according to the schema fails, the promise will be rejected with a `TypeValidationError`.

```ts file='index.ts' highlight={"17-26"}
import { streamObject } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
});

result.object
  .then(({ recipe }) => {
    // do something with the fully typed, final object:
    console.log('Recipe:', JSON.stringify(recipe, null, 2));
  })
  .catch(error => {
    // handle type validation failure
    // (when the object does not match the schema):
    console.error(error);
  });

// note: the stream needs to be consumed because of backpressure
for await (const partialObject of result.partialObjectStream) {
}
```
